Formation and capacity grading parallel detection system based on high-voltage direct-current bus

Abstract

The invention discloses a formation and capacity grading parallel detection system based on a high-voltage direct-current bus. A press device comprises a direct-current switch and at least one set of pull-out type charging and discharging probe module. And the input end of the direct-current switch is connected with the output end of the PCS equipment. Each charging and discharging probe module adopts a pull-out structure and comprises a mechanical frame, and a high-voltage direct-current bus, a bidirectional conversion module and a probe assembly which are integrally mounted in the mechanical frame; the high-voltage direct-current bus input end is connected with the direct-current switch output end; the bidirectional conversion module comprises two stages of conversion units; the first conversion unit is used for reducing the first voltage of the high-voltage direct-current bus into the second voltage or reversely increasing the voltage; the second conversion unit reduces the second voltage to the voltage required by charging and discharging of the battery or boosts the second voltage; the probe assembly is connected to the output end of the second conversion unit. The system is compact in structure, high in charging and discharging efficiency and convenient to maintain, and cables are saved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery production equipment technology, specifically to a parallel detection system for formation and capacity based on a high-voltage DC bus. Background Technology

[0002] Formation and capacity testing are crucial processes in lithium-ion battery manufacturing, involving multiple charge-discharge operations. In the production of prismatic lithium-ion batteries, the batteries are typically packed in groups on trays and subjected to charge-discharge tests using formation and capacity testing equipment. Since the terminals of prismatic lithium-ion batteries are mostly located on the upper surface, the probes of the testing system are usually designed to be positioned above the battery to achieve contact.

[0003] In traditional formation and capacity testing lines, equipment typically uses a 380V AC power supply system. Under this architecture, regardless of whether the equipment is charging or discharging, it must go through an AC-DC conversion stage: during charging, AC power must be converted to DC power to charge the battery, and during discharging, the DC power released by the battery must be inverted back to AC power to feed it back to the grid.

[0004] This method requires the AC-DC converter to pass through during battery charging and discharging, resulting in significant energy loss. Efficiency is particularly low when operating at low power (below half load) during AC-DC rectification and DC-AC inversion, leading to overall low system energy efficiency. Furthermore, traditional designs typically use one AC-DC module to power multiple DC-DC charging and discharging modules, relying on large-section power cables and copper busbars for connection. This not only occupies a large amount of equipment space but also increases system complexity and cost, and requires dismantling numerous cables for maintenance. Summary of the Invention

[0005] To overcome the technical shortcomings of existing chemical composition and capacity testing equipment, which connects each unit through long cables, resulting in long internal cables, high losses, severe heat generation, difficulty in maintenance, low space utilization, and large overall size, this invention provides a parallel detection system for chemical composition and capacity testing based on a high-voltage DC bus.

[0006] To solve the above problems, the present invention is implemented according to the following technical solution:

[0007] In a first aspect, the present invention provides a parallel testing system for battery formation and capacity testing based on a high-voltage DC bus, comprising a press device, the press device including: a DC switch, the input terminal of which is connected to the output terminal of a PCS device; at least one set of charge / discharge probe modules, the charge / discharge probe modules adopting a pull-out structure, each charge / discharge probe module including a mechanical frame and a high-voltage DC bus, a bidirectional conversion module, and a probe assembly integrated and installed within the mechanical frame; the output terminal of the DC switch is connected to the input terminal of the high-voltage DC bus; the bidirectional conversion module includes a first conversion unit and a second conversion unit, the input terminal of the first conversion unit being connected to the output terminal of the high-voltage DC bus, the input terminal of the second conversion unit being connected to the output terminal of the first conversion unit, and the output terminal of the second conversion unit being connected to the probe assembly; wherein, the first conversion unit is used to step down a first voltage output from the high-voltage DC bus to a second voltage, or step up the second voltage to the first voltage; the second conversion unit is used to step down the second voltage to a third voltage for battery charging and discharging, or step up the third voltage to the second voltage.

[0008] In conjunction with the first aspect, the present invention provides a first specific implementation of the first aspect. Specifically, when the charge / discharge probe module is installed in place and the press device performs a pressing action, the probe assembly forms an electrical connection with the terminal of the square-shell lithium battery in the tray under the pressing working conditions of the press device, so that the charge / discharge probe module and the square-shell lithium battery form a charge / discharge circuit through the probe assembly.

[0009] In conjunction with the first aspect, the present invention provides a second specific implementation of the first aspect. Specifically, the mechanical frame is provided with a guide groove, and the press device is provided with a guide rail adapted to the guide groove. When the mechanical frame is pushed in, the guide groove slides along the guide rail to achieve precise alignment between the charge / discharge probe module and the battery terminal.

[0010] In conjunction with the first aspect, the present invention provides a third specific implementation of the first aspect, wherein the input end of the bidirectional conversion module is connected to the high-voltage DC bus via a short cable or copper busbar.

[0011] In conjunction with the first aspect, the present invention provides a fourth specific embodiment of the first aspect. Specifically, the first conversion unit employs an LLC bidirectional converter circuit; the LLC bidirectional converter circuit includes a first gallium nitride transistor, a second gallium nitride transistor, a third gallium nitride transistor, a fourth gallium nitride transistor, a first inductor, a first capacitor, a second inductor, and a transformer; the positive terminal of the high-voltage DC bus is connected to the drain of the first gallium nitride transistor, and the negative terminal of the high-voltage DC bus is connected to the source of the second gallium nitride transistor; one end of the first inductor is connected between the source of the first gallium nitride transistor and the drain of the second gallium nitride transistor. The connection points are as follows: the other end of the first inductor is connected to the positive terminal of the first capacitor; one end of the primary side of the transformer is connected to the negative terminal of the first capacitor and one end of the second inductor, and the other end of the primary side of the transformer is connected to the other end of the second inductor and the source of the second gallium nitride transistor; the first output terminal of the secondary side of the transformer is connected to the drain of the third gallium nitride transistor, the source of the third gallium nitride transistor is connected to the source of the fourth gallium nitride transistor, and the drain of the fourth gallium nitride transistor is connected to the third output terminal of the secondary side of the transformer; the second output terminal of the secondary side of the transformer is connected to the second conversion unit.

[0012] In conjunction with the first aspect, the present invention provides a fifth specific embodiment of the first aspect, wherein the second conversion unit is composed of a bidirectional synchronous Buck / Boost circuit, the bidirectional synchronous Buck-Boost circuit being connected to the probe assembly.

[0013] In conjunction with the first aspect, the present invention provides a sixth specific implementation of the first aspect. Specifically, during charging, the first voltage provided by the PCS device is transmitted to the first conversion unit via the high-voltage DC bus for step-down to obtain a second voltage, which is then stepped down and adjusted by the second conversion unit to a third voltage suitable for battery charging, and finally charged to the prismatic lithium battery via the probe assembly. During discharging, the third voltage DC output by the prismatic lithium battery is transmitted to the second conversion unit via the probe assembly for step-up to obtain the second voltage, which is then stepped up and adjusted by the first conversion unit to the first voltage, and finally fed back to the PCS device or electrical equipment via the high-voltage DC bus.

[0014] In conjunction with the first aspect, the present invention provides a seventh specific implementation of the first aspect, specifically, a control system, the control system including a central computer, an IO control unit and a temperature fan unit; the central computer is connected to the IO control unit and the temperature fan unit respectively.

[0015] In conjunction with the first aspect, the present invention provides an eighth specific implementation of the first aspect, wherein the intermediate unit is used to send charging and discharging commands to the charging and discharging probe module and to collect data from the prismatic lithium battery.

[0016] In conjunction with the first aspect, the present invention provides a ninth specific embodiment of the first aspect. Specifically, the temperature fan unit includes: a temperature sensor for real-time acquisition of temperature data within the prismatic lithium battery and the press device; a fan drive unit connected to the central computer and receiving the temperature data; and a cooling fan mounted on the frame of the press device. The central computer controls the operation of the cooling fan based on the temperature data through the fan drive unit to dissipate heat from the prismatic lithium battery and the press device.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] A parallel testing system for capacity and load testing based on a high-voltage DC bus integrates the high-voltage DC bus, bidirectional conversion module, signal bus board, and probes within a mechanical frame using a pull-out charge / discharge probe module. Externally, only one high-voltage, low-current input and one communication bus are required. Internal wiring is short and neat, fundamentally eliminating messy cables and achieving extremely high space utilization. Simultaneously, it improves system power conversion efficiency and reduces cooling requirements. The integrated design significantly reduces the space occupied by internal cables, providing unobstructed airflow channels for power device heat dissipation. The pull-out structure of the charge / discharge probe module simplifies the equipment maintenance process, eliminating the need for operators to disassemble and reassemble complex wiring harnesses, significantly improving maintenance efficiency. Attached Figure Description

[0019] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0020] Figure 1 This is a schematic diagram of the structural framework of a parallel detection system for the composition and capacity of a high-voltage DC bus based on the present invention.

[0021] Figure 2 This is a circuit connection diagram of the bidirectional conversion module of the present invention.

[0022] Illustration:

[0023] 1-Charge / discharge probe module; 2-Control system; 3-First conversion unit; 4-Second conversion unit. Detailed Implementation

[0024] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0025] In existing technologies, the lithium battery formation and capacity testing process requires multiple charge-discharge operations. Traditional equipment uses a 380V AC power supply system, and the charge-discharge process requires AC-DC and DC-AC conversion, resulting in significant energy loss. At the same time, one AC-DC module corresponds to multiple DC-DC charge-discharge modules, and the AC-DC and DC-DC are connected through power cables or copper busbars. Due to the large size of the cables and copper busbars, they occupy a lot of internal space in the formation and capacity testing equipment.

[0026] To address the aforementioned issues, the traditional AC-DC conversion stage leads to low system efficiency and consumes space due to large-section cables. Introducing a high-voltage DC bus for direct power supply eliminates intermediate conversion losses. Designing a pull-out charge / discharge probe module optimizes space utilization, and integrating a bidirectional conversion module enables bidirectional adjustment of high and low voltages, thereby constructing a compact and efficient charge / discharge circuit.

[0027] like Figures 1-2 As shown, this invention provides a parallel detection system for the composition and capacity of a high-voltage DC bus.

[0028] Example 1

[0029] A parallel testing system for battery formation and capacity testing based on a high-voltage DC bus includes a press device. The press device includes: a DC switch, the input of which is connected to the output of a PCS device; at least one set of charge / discharge probe modules 1, each charge / discharge probe module 1 having a pull-out structure, each charge / discharge probe module 1 including a mechanical frame and a high-voltage DC bus, a bidirectional conversion module, a signal bus board, and a probe assembly integrated within the mechanical frame; the input of the high-voltage DC bus is connected to the output of the DC switch; the bidirectional conversion module includes a first conversion unit 3 and a second conversion unit 4, the input of the first conversion unit 3 being connected to the output of the high-voltage DC bus, the input of the second conversion unit 4 being connected to the output of the first conversion unit 3, and the output of the second conversion unit 4 being connected to the probe assembly; wherein, the first conversion unit 3 is used to step down a first voltage output from the high-voltage DC bus to a second voltage, or step up the second voltage to the first voltage; the second conversion unit 4 is used to step down the second voltage to a third voltage for battery charging and discharging, or step up the third voltage to the second voltage; the signal bus board is communicatively connected to the bidirectional conversion module via parallel signal lines.

[0030] Specifically, the press unit mainly includes a DC switch and a charge / discharge probe module 1. The input terminal of the DC switch is connected to the high-voltage DC bus via a cable (high-voltage input current is small) to receive 750V DC power. The switching on and off of the DC switch is controlled by the main control system, serving as the main power switch for the entire press unit. Each press unit has at least one set of charge / discharge probe modules 1 installed. Each set of charge / discharge probe modules 1 adopts a pull-out drawer structure for easy and quick maintenance and replacement. All components of a single charge / discharge probe module 1 are integrated and installed within the mechanical frame. A guide groove is provided on the lower part of both sides of the mechanical frame. Corresponding guide rails are provided on the fixed frame of the press unit. During maintenance, the operator can pull out the entire charge / discharge probe module 1 smoothly along the guide rails like pulling out a drawer; when pushing it back in, the guide grooves ensure that the charge / discharge probe module 1 is accurately reset, achieving automatic alignment of the probe assembly with the battery terminals in the tray below. The input terminal of the high-voltage DC bus is connected to the copper busbar of the output terminal of the DC switch to receive 750V DC power. Multiple output terminals are designed on the high-voltage DC bus for distributing electrical energy. The bidirectional conversion module is electrically connected to the output interface of the high-voltage DC bus, using short cables or copper busbars for direct connection to reduce parasitic inductance.

[0031] The bidirectional conversion module consists of two cascaded units: the first conversion unit 3 achieves bidirectional isolated conversion between 750V high-voltage DC and 12V (typical) intermediate DC. That is, the first voltage is 750V high-voltage DC, and the second voltage is 12V intermediate DC. The first conversion unit 3 uses an LLC bidirectional converter circuit to convert 750V to 12V during charging and 12V to 750V during discharging. Specifically, gallium nitride transistors can be used to achieve high efficiency, high power density, and small size. This unit is responsible for most of the voltage conversion span and provides electrical isolation. The second conversion unit 4 achieves bidirectional non-isolated conversion between the 12V intermediate DC and the battery voltage (typically 1.5V to 5V). That is, the third voltage is set according to the voltage required by the prismatic lithium battery, and the requirements vary depending on the model. The second conversion unit 4 uses a bidirectional synchronous Buck / Boost circuit, which is connected to the probe assembly. The second conversion unit 4 is responsible for constant current, constant voltage charging, and constant current discharging control for each prismatic lithium battery. The input terminals of the probe assembly are connected one-to-one with the output terminals of the second conversion unit 4.

[0032] The operator pushes the tray filled with batteries to be tested into the press station. The press is started, and it performs the pressing action. Guided by the guide rail, the charge / discharge probe module 1 ensures that the probe assembly makes reliable contact with the terminals of all the prismatic lithium batteries in the tray simultaneously, forming an electrical connection. After the operator closes the DC switch, the central control system issues a command to the press to enter working mode, and 750V DC power is sent to the high-voltage DC bus. The first conversion unit 3 operates in Buck mode, efficiently reducing 750V to 12V. The Buck / Boost circuits in each channel of the second conversion unit 4 operate in Buck mode according to the command, converting 12V into the charging voltage and current required by the batteries in the tray, and performing constant current / constant voltage charging on the batteries through the probe assembly. During charging, the voltage and current data of each channel are uploaded to the central control system via communication for monitoring and recording. The Buck / Boost circuits in each channel of the second conversion unit 4 operate in Boost mode, boosting the energy discharged by the battery from the battery voltage to 12V. The first conversion unit 3 (LLC converter) operates in Boost mode, boosting the DC 12V back to DC 750V and feeding energy back to the high-voltage DC bus for use by other charging stations or for feedback to the grid via the PCS, thus achieving energy savings. The system also performs constant current control and data acquisition during the discharge process. After the test is completed, the press device rises, and the probe assembly separates from the battery. The operator removes the tray, and the process ends.

[0033] More specifically, the high-voltage DC bus is connected to the charge / discharge probe module 1 via a DC switch, and electrical energy is transmitted to the bidirectional conversion module via the high-voltage DC bus. During charging, the high-voltage DC is stepped down to a second voltage by the first conversion unit 3, then adjusted to the battery charging voltage by the second conversion unit 4, and finally delivered to the battery terminals by the probe assembly. During discharging, the electrical energy released by the battery returns to the bidirectional conversion module via the probe assembly, is sequentially stepped up to the second voltage and then the first voltage, and fed back to the high-voltage DC bus via the high-voltage DC bus. The system sends control commands to the bidirectional conversion module via communication to adjust the voltage conversion parameters, while simultaneously collecting battery status data. The guide groove of the mechanical frame cooperates with the guide rail in the press device to ensure precise alignment of the probe assembly with the battery terminals during the pressing process.

[0034] Compared to existing technologies, traditional solutions rely on multi-stage AC-DC conversion, leading to energy loss and increased equipment size. This solution directly supplies power via a high-voltage DC bus, eliminating intermediate conversion stages, significantly reducing cable length, and achieving efficient bidirectional energy flow through a bidirectional conversion module. The pull-out design of the charge / discharge probe module 1 replaces the traditional fixed installation method, simplifying maintenance and optimizing space layout.

[0035] Through the above technical solutions, this application solves the problems of high energy loss and low space utilization in traditional batching and capacity testing equipment. Direct power supply from the high-voltage DC bus reduces conversion losses, the bidirectional conversion module achieves efficient energy regulation during charging and discharging, the pull-out charge / discharge probe module 1 improves the modularity and maintenance convenience of the equipment, and the guiding structure ensures reliable contact between the probe and the battery terminal, thereby improving the overall efficiency and stability of the system.

[0036] In a preferred embodiment, the PCS device is a bidirectional power conversion unit that performs AC-DC conversion and connects the three-phase AC power grid and the high-voltage DC bus. The PCS device generally consists of a power frequency isolation transformer, a bidirectional AC-DC converter, AC-DC switches, control and indication components, etc. It automatically operates in rectification or inversion mode according to the power conditions on the high-voltage DC bus, and realizes control of power factor, voltage harmonics, current harmonics, etc., to ensure the power quality of the three-phase AC power grid.

[0037] In a preferred embodiment, when the charge / discharge probe module 1 is installed in place and the press device performs the pressing action, the probe assembly forms an electrical connection with the terminal of the square-shell lithium battery in the tray under the pressing working conditions of the press device, so that the charge / discharge probe module 1 and the square-shell lithium battery form a charge / discharge circuit through the probe assembly.

[0038] Specifically, the installation of the charge / discharge probe module 1 means that the module is positioned through the sliding engagement of the guide groove and the guide rail. This can be achieved using a slide rail mechanism with a positioning sensor to ensure the physical alignment of the probe assembly with the terminal of the prismatic lithium battery. The pressing action refers to the application of vertical mechanical pressure by the press device, which can be achieved using a hydraulic cylinder or servo motor drive, with the pressing force monitored in real time by a pressure sensor. Electrical connection refers to the formation of a low-impedance conductive path between the conductive contacts of the probe assembly and the surface of the battery terminal. This can be achieved using an elastic probe, which maintains contact pressure through elastic deformation during the pressing process. The charge / discharge circuit is a closed circuit consisting of a high-voltage DC bus, a bidirectional conversion module, the probe assembly, and the battery. The direction of current can be controlled by the power switching devices of the bidirectional conversion module to achieve bidirectional flow of electrical energy.

[0039] More specifically, after the charge / discharge probe module 1 is fully pushed in along the guide rail, the drive mechanism of the press device begins to perform a vertical pressing action. As the pressure plate moves downward, the elastic probe in the probe assembly makes physical contact with the surface of the battery terminal under mechanical pressure. At this time, the compression stroke of the probe reaches the preset value, and the contact resistance is controlled within the allowable range. When the pressing action is completed, the input end of the bidirectional conversion module is connected to the DC switch through the high-voltage DC bus, and the output end is connected to the battery terminal through the probe assembly, forming a complete power transmission channel. In charging mode, the high-voltage DC power is stepped down by the bidirectional conversion module and then input to the battery through the probe assembly; in discharging mode, the power released by the battery is transmitted to the bidirectional conversion module through the probe assembly, stepped up, and then fed back to the high-voltage DC bus. This solution automatically completes precise alignment during the pushing of the charge / discharge probe module 1 through the synergistic effect of the mechanical pressing action of the press device and the guide structure, and ensures the reliability of the electrical connection through controllable mechanical pressure during the pressing stage, eliminating the need for manual intervention. Meanwhile, the formation of the charging and discharging circuit is completed simultaneously with the pressing action, avoiding the need for separate electrical connection operations in traditional solutions.

[0040] In a preferred embodiment, the mechanical frame is provided with a guide groove, and the press device is provided with a guide rail adapted to the guide groove; when the mechanical frame is pushed in, the guide groove slides along the guide rail to achieve precise alignment between the charge / discharge probe module 1 and the battery terminal.

[0041] Specifically, the guide groove refers to a groove structure set on the side of the mechanical frame, which can be implemented with a V-shaped or U-shaped cross-section design. It is used to form a sliding fit with the guide rail to restrict the degree of freedom of movement of the charge / discharge probe module 1 during the pushing process. The guide rail refers to a protruding structure fixed in the press device, whose cross-sectional shape is complementary to the guide groove, and is used to guide the mechanical frame to move along a predetermined path.

[0042] More specifically, during the installation of the charge / discharge probe module 1, the operator pushes the mechanical frame along the guide rail of the press device. The fit between the guide groove and the guide rail allows the charge / discharge probe module 1 to slide only along a single axis, preventing lateral swaying or tilting. This solves the problem of low alignment accuracy between the probe and the prismatic lithium battery terminal, avoiding the risk of poor contact or short circuits caused by human error, while simplifying the module installation process and significantly improving equipment maintenance efficiency and operational safety. When the mechanical frame is fully pushed into place, the position of the probe assembly is aligned with the position of the prismatic lithium battery terminal in the tray. At this point, the press device performs a pressing action, establishing a stable electrical contact between the probe assembly and the prismatic lithium battery terminal.

[0043] In a preferred embodiment, the input terminal of the bidirectional conversion module is connected to the high-voltage DC bus via a short cable or copper busbar.

[0044] Specifically, the short cable refers to the short installation distance between the bidirectional conversion module and the high-voltage DC bus, requiring only a very short cable. This can be achieved using multi-strand stranded copper core wire or flat wire harnesses, reducing line impedance and energy loss by shortening the current transmission path. The copper busbar refers to a flat conductor made of a highly conductive metal material, specifically a tin-plated copper busbar, used to carry high current transmission and reduce contact resistance.

[0045] More specifically, during the internal assembly of the charge / discharge probe module 1, the bidirectional conversion module is integrated within the mechanical frame. Its input end is directly welded or crimped to the output port of the high-voltage DC bus via a short cable, thus controlling the power transmission path within the charge / discharge probe module 1. Alternatively, the copper busbar is designed with an L-shaped or U-shaped bend structure, forming a surface contact connection with the high-voltage DC bus, thereby achieving a low-impedance, high-current-carrying electrical connection within a limited space. Both connection methods avoid the long-distance wiring across modules found in traditional equipment, improving the energy transmission efficiency between the high-voltage DC bus and the bidirectional conversion module, while reducing electromagnetic interference caused by line redundancy.

[0046] In a preferred embodiment, the first conversion unit 3 employs an LLC bidirectional converter circuit; the LLC bidirectional converter circuit includes a first gallium nitride transistor, a second gallium nitride transistor, a third gallium nitride transistor, a fourth gallium nitride transistor, a first inductor, a first capacitor, a second inductor, and a transformer; the positive terminal of the high-voltage DC bus is connected to the drain of the first gallium nitride transistor, and the negative terminal of the high-voltage DC bus is connected to the source of the second gallium nitride transistor; one end of the first inductor is connected to the connection point between the source of the first gallium nitride transistor and the drain of the second gallium nitride transistor, and the first inductor... The other end of the transformer is connected to the positive terminal of the first capacitor; one end of the primary side of the transformer is connected to the negative terminal of the first capacitor and one end of the second inductor, and the other end of the primary side of the transformer is connected to the other end of the second inductor and the source of the second gallium nitride transistor; the first output terminal of the secondary side of the transformer is connected to the drain of the third gallium nitride transistor, the source of the third gallium nitride transistor is connected to the source of the fourth gallium nitride transistor, and the drain of the fourth gallium nitride transistor is connected to the third output terminal of the secondary side of the transformer; the second output terminal of the secondary side of the transformer is connected to the second conversion unit 4.

[0047] Specifically, one end of the primary side of the transformer, the first output terminal of the secondary side of the transformer, and the second output terminal of the secondary side of the transformer are all terminals with the same name; the other end of the primary side of the transformer and the third output terminal of the secondary side of the transformer are terminals with different names.

[0048] When the first conversion unit 3 operates in the mode of converting the first voltage (750V) to the second voltage (12V), the first gallium nitride transistor and the second gallium nitride transistor form a half-bridge to convert the high-voltage DC current into a high-frequency AC square wave. The body diodes of the third and fourth gallium nitride transistors act as a rectifier bridge to rectify the high-frequency AC current on the secondary side of the transformer into DC current. The first inductor, the first capacitor, and the second inductor constitute an LLC resonant network. Specifically: the first inductor is the resonant inductor; the first capacitor is the resonant capacitor; and the second inductor is the magnetizing inductance of the transformer (the second inductor is connected in parallel to the resonant cavity). The first and second gallium nitride transistors conduct alternately, generating a square wave voltage at the connection point between the source of the first gallium nitride transistor and the drain of the second gallium nitride transistor. This square wave voltage is applied to the LLC resonant network. By designing the values ​​of the first inductor, the first capacitor, and the second inductor, the switching frequency fs is made close to the resonant frequency fr of the resonant network. At this time, the resonant current exhibits a sinusoidal shape and lags behind the square wave voltage. Due to current lag, when the first gallium nitride transistor (GaN) is to be turned off, the current direction has already reversed. This reverse current drains the junction capacitance charge of the first GaN transistor and charges the junction capacitance of the second GaN transistor. When the voltage of the first GaN transistor drops to zero, the second GaN transistor is turned on again, achieving zero-voltage turn-on (ZVS). Similarly, the second GaN transistor can also achieve ZVS turn-off. This is the core of the high efficiency of LLC. The sinusoidal current is stepped down by the transformer and then transmitted to the secondary side. The third and fourth GaN transistors on the secondary side act as synchronous rectifiers, rectifying the AC current into DC current when their body diodes are naturally conducting, and outputting it to the second conversion unit 4.

[0049] When the first conversion unit 3 operates in the mode of converting the second voltage (12V) to the first voltage (750V), the third and fourth gallium nitride transistors form an active half-bridge, acting as an inverter to convert low-voltage DC to high-frequency AC. The body diodes of the first and second gallium nitride transistors act as a rectifier bridge, rectifying the high-frequency AC on the primary side of the transformer into high-voltage DC. The third and fourth gallium nitride transistors invert the low-voltage DC (12V) into an AC square wave, which is then boosted by the transformer and transmitted to the primary side. The resonant network on the primary side also operates. At this time, the first and second gallium nitride transistors on the primary side operate as synchronous rectifiers. Since the resonance mechanism remains unchanged, in reverse mode, the first and second gallium nitride transistors on the primary side can also achieve ZVS, ensuring efficiency during reverse operation.

[0050] In a preferred embodiment, the second conversion unit 4 is composed of a bidirectional synchronous Buck / Boost circuit, which is connected to the probe assembly.

[0051] The bidirectional synchronous Buck / Boost circuit refers to a bidirectional power electronic converter circuit capable of voltage boosting and scaling according to charging and discharging requirements. Specifically, it uses MOSFETs as switching devices, combined with inductors, capacitors, and control logic to achieve bidirectional energy flow. In charging mode, this circuit acts as a buck converter, supplying 12V DC to the voltage required for battery charging. In discharging mode, it acts as a boost converter, boosting the low-voltage DC output from the battery to the high-voltage DC bus voltage.

[0052] Specifically, when the probe assembly forms an electrical connection with the battery terminals, the control system 2 adjusts the duty cycle of the switching transistor according to the charging and discharging commands. During the charging phase, the 12V DC voltage output by the first conversion circuit is stepped down and then output to the battery; during the discharging phase, the low-voltage electrical energy output by the battery is boosted to 12V and supplied to the first conversion circuit.

[0053] In a preferred embodiment, the bidirectional synchronous Buck / Boost circuit includes a first transistor, a second transistor, a third inductor, and a second capacitor; the source of the first transistor is connected to the drain of the second transistor, the source of the second transistor is connected to the negative terminal of the second capacitor, and the positive terminal of the second capacitor is connected to the connection point between the source of the first transistor and the drain of the second transistor through the third inductor.

[0054] Specifically, when the LLC output voltage is higher than the low-voltage battery voltage, the circuit operates in synchronous Buck buck mode. The first transistor acts as the control switch, and the second transistor acts as the synchronous rectifier (conducting when the first transistor is off). When the first transistor is on, the current path is: LLC output → first transistor → third inductor → battery. The third inductor stores energy. When the first transistor is off, since the inductor current cannot change abruptly, the third inductor generates an induced electromotive force, forming a freewheeling circuit through the body diode of the first transistor, and the current continues to flow to the battery.

[0055] When the high-voltage side needs charging while the low-voltage side is low, the circuit operates in synchronous Boost mode. The second transistor acts as a control switch (high-frequency switch), and the first transistor acts as a synchronous rectifier (conducting when the second transistor is off). When the second transistor is on, the current path is: battery → third inductor → second transistor → first switching unit. When the second transistor is off, the inductor current cannot change abruptly. The induced electromotive force generated by the third inductor is superimposed on the battery voltage and flows through the body diode of the first transistor to the LLC circuit.

[0056] In a preferred embodiment, during charging, the first voltage provided by the PCS device is transmitted to the first conversion unit 3 via the high-voltage DC bus for step-down to obtain a second voltage, which is then stepped down and adjusted by the second conversion unit 4 to a third voltage suitable for battery charging, and finally charged to the prismatic lithium battery via the probe assembly; during discharging, the third voltage DC output by the prismatic lithium battery is transmitted to the second conversion unit 4 via the probe assembly for step-up to obtain the second voltage, which is then stepped up and adjusted by the first conversion unit 3 to the first voltage, and finally fed back to the PCS device or electrical equipment via the high-voltage DC bus.

[0057] The 750V high-voltage direct current (HVDC) refers to the DC power transmitted through the high-voltage DC bus, serving as the energy input source for the entire system. The bidirectional conversion module is a power electronic device with bidirectional voltage conversion capabilities, specifically implemented using a combination of LLC resonant converter circuits and Buck / Boost circuits to achieve bidirectional energy flow between high-voltage and low-voltage DC. Buck regulation converts the 750V HVDC into low-voltage DC suitable for lithium battery charging. Boost regulation converts the low-voltage DC output from the lithium battery into a voltage level matching the high-voltage DC bus. The PCS (Power Conversion System) refers to an energy storage converter device, specifically implemented using power electronic devices with bidirectional inverter capabilities, used to convert the boosted DC into AC power to feed back to the grid or supply local loads.

[0058] Specifically, in charging mode, the 750V DC power provided by the PCS device is directly transmitted to the bidirectional conversion module via the high-voltage DC bus. After a first-stage step-down conversion by the LLC resonant converter, it undergoes a second-stage voltage regulation via the Buck / Boost circuit, ultimately outputting low-voltage DC power that meets the charging requirements of the lithium battery. In discharging mode, the low-voltage DC power released by the lithium battery undergoes a first-stage step-up conversion via the Buck / Boost circuit. After adjustment by the LLC resonant converter, it forms a voltage level that matches the high-voltage DC bus, which can power other parallel devices or be used for energy feedback through the PCS device. The voltage conversion process is reduced to two stages and eliminates the need for AC conversion.

[0059] In a preferred embodiment, the control system 2 includes a central computer, an I / O control unit, and a temperature fan unit; the central computer is connected to the I / O control unit and the temperature fan unit respectively.

[0060] Specifically, the intermediate control unit refers to a control unit with data processing and instruction distribution functions. It can be implemented using an embedded industrial computer or a PLC controller, establishing communication links with each functional unit via a data bus. The I / O control unit is an interface module that implements digital signal input and output. It can be implemented using a relay array with isolation protection or an optocoupler circuit, used to convert the press's action signals into logical instructions recognizable by the intermediate control unit. The temperature fan unit is a module integrating temperature monitoring and heat dissipation control. It can be implemented using a temperature sensor in conjunction with a PWM speed control circuit, used to collect real-time data on the internal temperature of the press and the battery temperature, and adjust the operating status of the cooling fan.

[0061] Specifically, the host computer sends a pressing action command to the IO control unit via a parallel communication protocol, triggering the electrical connection between the charge / discharge probe module 1 and the battery terminals. During the charging and discharging process, the temperature fan unit continuously collects temperature data from the battery and the press device and transmits it to the host computer via an analog signal interface. When the temperature exceeds a preset threshold, the host computer sends a control signal to the fan drive unit to activate the cooling fan for forced air cooling. Simultaneously, the IO control unit provides real-time feedback on the probe contact status and press position information to ensure the safe connection and disconnection of the charging and discharging circuit.

[0062] In a preferred embodiment, the intermediate unit is connected to the signal busboard via a signal interface board, and is used to send charging and discharging commands to the charging and discharging probe module 1 and collect data from the prismatic lithium battery.

[0063] Specifically, the intermediate unit refers to the core processing unit of the control system 22, which can be implemented using an industrial control computer or an embedded controller, and is used to coordinate the generation and data transmission of charging and discharging commands. The signal interface board is a hardware module installed on the maintenance side of the charging and discharging probe module 1, facilitating signal line conversion. The signal bus board is the circuit carrier integrating the communication transmission path, which can be implemented using a multi-layer PCB board, and is used to establish a distributed communication channel with the bidirectional conversion module.

[0064] More specifically, the intermediate control unit establishes a communication connection with the signal bus board via the signal interface board. Charging and discharging commands are transmitted via the signal bus board to each bidirectional conversion module, triggering them to perform voltage conversion operations. In charging mode, the intermediate control unit issues a step-down command, causing the bidirectional conversion module to convert the high-voltage DC power to a charging voltage suitable for the lithium battery. In discharging mode, the intermediate control unit issues a step-up command, causing the bidirectional conversion module to boost the low-voltage DC power output from the lithium battery and feed it back to the high-voltage DC bus. Simultaneously, the signal bus board collects real-time voltage, current, and temperature data from the lithium battery and transmits this data back to the intermediate control unit via the signal interface board, forming a closed-loop control system. The combined structure of the signal interface board and the signal bus board replaces the traditional distributed cable connections, integrating the command and data transmission paths within the mechanical frame and avoiding long-distance cable routing.

[0065] In a preferred embodiment, the temperature fan unit includes: a temperature sensor for real-time acquisition of temperature data within the prismatic lithium battery and the press device; a fan drive unit connected to the central control unit and receiving the temperature data; and a cooling fan mounted on the frame of the press device. The central control unit controls the operation of the cooling fan based on the temperature data through the fan drive unit to dissipate heat from the prismatic lithium battery and the press device.

[0066] Specifically, a temperature sensor is a device used to detect temperature changes inside the battery and equipment. It can be implemented using thermocouples or thermistors, converting temperature signals into electrical signals and transmitting them to a central control unit for real-time temperature monitoring. The fan drive unit is a circuit module that controls the operation of the cooling fan, typically implemented using a PWM controller or relay drive circuit. It adjusts the fan speed or starts / stops by receiving control signals from the central control unit. The cooling fan is a mechanical device used to force airflow, typically a centrifugal fan or axial fan. Installed at a pre-defined airflow location within the press frame, it creates directional airflow to achieve heat dissipation.

[0067] More specifically, temperature sensors are placed in the battery tray contact area and key heat-generating components inside the press unit. When the detected temperature exceeds a preset threshold, the central control unit sends a control command to the fan drive unit via the signal interface board, driving the cooling fan to operate at the corresponding speed. The cooling fan adjusts its operating state according to the command, and the generated airflow directly acts on the surface of the prismatic lithium battery, with heat being discharged through the exhaust vents inside the press unit. The temperature sensors continuously collect real-time temperature data of the prismatic lithium battery and upload the data to the central control unit; the central control unit analyzes the temperature data to generate control commands and transmits the commands to the fan drive unit; the fan drive unit dynamically adjusts the speed of the cooling fan based on the feedback signal from the temperature sensor, ensuring that the airflow generated matches the heat dissipation requirements of the prismatic lithium battery. The cooling fan, mounted on the frame of the press unit, dissipates heat from the surface of the prismatic lithium battery, thereby maintaining the temperature stability of the prismatic lithium battery during charging and discharging.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high-voltage direct-current bus-based formation and parallel detection system in cell, comprising a pressing device, characterized in that, The press device comprises: A direct current switch, the input end of which is connected to the output end of the PCS device; At least one set of charging and discharging probe modules, each of which comprises a mechanical frame and a high-voltage direct-current bus, a bidirectional conversion module and a probe assembly integrated in the mechanical frame, and adopts a pull-out structure; The output end of the direct current switch is connected to the input end of the high-voltage direct-current bus; The bidirectional conversion module comprises a first conversion unit and a second conversion unit, the input end of the first conversion unit is connected to the output end of the high-voltage direct-current bus, the input end of the second conversion unit is connected to the output end of the first conversion unit, and the output end of the second conversion unit is connected to the probe assembly; The first conversion unit is used to step down the first voltage output by the high-voltage direct-current bus to a second voltage or step up the second voltage to the first voltage; The second conversion unit is used to step down the second voltage to a third voltage for battery charging and discharging or step up the third voltage to the second voltage.

2. The high-voltage direct-current bus-based formation and parallel detection system according to claim 1, characterized in that: When the charging and discharging probe module is installed in place and the press device performs a pressing action, the probe assembly forms an electrical connection with the pole of the prismatic lithium battery in the tray under the pressing working condition of the press device, so that the charging and discharging probe module forms a charging and discharging circuit with the prismatic lithium battery through the probe assembly.

3. The high-voltage direct-current bus-based formation and parallel detection system according to claim 1, characterized in that: The mechanical frame is provided with a guide groove, and the press device is correspondingly provided with a guide rail matched with the guide groove; When the mechanical frame is pushed in, the guide groove slides along the guide rail to realize accurate alignment of the charging and discharging probe module with the battery pole.

4. The high-voltage direct-current bus-based formation and parallel detection system according to claim 1, characterized in that: The input end of the bidirectional conversion module is connected to the high-voltage direct-current bus through a short cable or a copper bar.

5. The high-voltage direct-current bus-based formation and parallel detection system according to claim 1, characterized in that: The first conversion unit adopts an LLC bidirectional conversion circuit; The LLC bidirectional conversion circuit comprises a first gallium nitride transistor, a second gallium nitride transistor, a third gallium nitride transistor, a fourth gallium nitride transistor, a first inductor, a first capacitor, a second inductor and a transformer; The positive pole of the high-voltage direct-current bus is connected to the drain of the first gallium nitride transistor, and the negative pole of the high-voltage direct-current bus is connected to the source of the second gallium nitride transistor; One end of the first inductor is connected to a connection point between the source of the first gallium nitride transistor and the drain of the second gallium nitride transistor, and the other end of the first inductor is connected to the positive pole of the first capacitor; One end of the primary side of the transformer is respectively connected to the negative pole of the first capacitor and one end of the second inductor, and the other end of the primary side of the transformer is respectively connected to the other end of the second inductor and the source of the second gallium nitride transistor. The first output end of the secondary side of the transformer is connected to the drain of the third gallium nitride transistor, the source of the third gallium nitride transistor is connected to the source of the fourth gallium nitride transistor, and the drain of the fourth gallium nitride transistor is connected to the third output end of the secondary side of the transformer. The second output end of the secondary side of the transformer is connected to the second conversion unit.

6. The parallel detection system based on the high-voltage DC bus for formation and capacity of the lithium battery according to claim 1, characterized in that: The second conversion unit adopts a bidirectional synchronous Buck / Boost circuit, and the bidirectional synchronous Buck / Boost circuit is connected to the probe assembly.

7. The parallel detection system based on the high-voltage DC bus for formation and capacity of the lithium battery according to claim 1, characterized in that: During charging, the first voltage provided by the PCS device is transmitted to the first conversion unit through the high-voltage DC bus for voltage reduction, to obtain the second voltage, and then the second voltage is transmitted to the second conversion unit for voltage reduction and adjustment to obtain the third voltage suitable for battery charging, and finally the third voltage is transmitted to the square lithium battery through the probe assembly for charging; During discharging, the third voltage DC output by the square lithium battery is transmitted to the second conversion unit through the probe assembly for voltage increase, to obtain the second voltage, and then the second voltage is transmitted to the first conversion unit for voltage increase and adjustment to obtain the first voltage, and finally the first voltage is fed back to the PCS device or the power consumption device through the high-voltage DC bus. 8.The high-voltage DC bus-based formation and parallel detection system according to any one of claims 1-7, characterized in that, Further comprising: A control system, wherein the control system comprises a central machine, an IO control unit and a temperature fan unit; The central machine is connected to the IO control unit and the temperature fan unit respectively.

9. The parallel detection system based on the high-voltage DC bus for formation and capacity of the lithium battery according to claim 8, characterized in that: The central machine is used to issue charging and discharging instructions to the charging and discharging probe module and collect data of the square lithium battery.

10. The high-voltage DC bus-based formation and parallel detection system according to claim 9, wherein, The temperature fan unit comprises: A temperature sensor, which is used to collect temperature data of the square lithium battery and the press device in real time; A fan driving unit, which is connected to the central machine and receives the temperature data; A cooling fan, which is installed on the frame of the press device, and the central machine controls the operating state of the cooling fan through the fan driving unit based on the temperature data, to cool the square lithium battery and the press device.

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